The present invention is in the field of catalysts, as used for example in methods for the production of polymers. The invention relates in particular to catalysts based on double metal cyanide compounds and proposes a novel catalyst of this type.
Double metal cyanide complex compounds (DMC complex compounds) are known in principle as catalysts, e.g. for the polymerization of epoxides. For example, polyethers that are distinguished by a particularly narrow molecular weight distribution, a high average molar mass and a very low number of double bonds at the ends of the polymer chains can be produced using catalysts of this type. However, DMC catalysts can also be used to produce other polymers, e.g. polyesters.
There is increasing interest in methods for the catalyzed conversion of epoxides and carbon dioxide to copolymers that are used as starting compounds for foams, adhesives, composite materials, fibers and fiber components, films, membranes or membrane components and resins. Methods of this type are described e.g. in DE19737547 A1. As the catalyst system here, a mixture of at least two dicarboxylic acids and an inorganic zinc compound is used.
WO2004/087788 A1 describes a method for polyol production, which encompasses the step of reacting an initiator with an alkylene oxide in the presence of a DMC catalyst and a sterically hindered chain transfer agent, wherein the chain transfer agent is capable of protonating the growing polyol polymer.
U.S. Pat. No. 5,026,676 describes a zinc carboxylate catalyst for the copolymerization of carbon dioxide with epoxides, which is produced by reacting zinc oxide with glutaric acid or adipic acid in an aprotic solvent.
EP0222453 A2 describes a method for producing polycarbonate, which encompasses the reaction of an epoxy compound with carbon dioxide and is carried out in the presence of a double metal cyanide complex. The double metal cyanide complex contains as possible ligands an alcohol, ester, aldehyde, ketone, ether, amide, nitrile, sulfide or a mixture thereof. Furthermore, the general formula of the double metal cyanide complex comprises a hydrocarbon.
EP0700949 A2 provides double metal cyanide catalysts (DMC catalysts), which encompass a DMC complex, an organic complexing agent and, based on the quantity of catalyst, 5-80 wt % of a polyether with a number average molecular weight of more than about 500.
CN1459332 A describes a DMC catalyst which, in addition to a double metal cyanide complex, encompasses a soluble metal salt, an organic complexing agent and an organopolysiloxane as well as, optionally, a polyether polyol.
There is a continuing need for catalysts that efficiently catalyze the polymerization of epoxides, thus making possible a cost-efficient method for producing epoxide-based polymers.